Automatic Activity Arising in Cardiac Muscle Sleeves of the Pulmonary Vein

Figures

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  Figure 1. Automatic activity in cardiac muscle of the PV produced by the combination of α- and β-adrenergic receptor stimulation. Traces represent isolated segments of an otherwise continuous recording of membrane potential in cardiac muscle of one PV during the superfusion of 1 µM Cirazoline and different concentrations of isoprenaline. Modified from Doisne et al. [33].

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  Figure 2. An intracellular microelectrode recording from an isolated PV of the rat. These traces form parts of an otherwise continuous recording during one penetration. (a) Automatic activity which had been evoked by the superfusion of 5 µM NE presented as continuous firing (3.8 Hz) of action potentials arising from a diastolic membrane potential of −69 mV, overshooting to +4 mV with a maximum rate of phase 0 depolarization of 5.4 V/s. Ten minutes after reducing the concentration of NE to 2 µM, continuous firing was replaced by automatic activity representing as bursts separated by silent intervals. Details of individual automatic action potentials recorded under these conditions are shown upon an expanded scale in (b).